Struct Ptr 

pub struct Ptr { /* private fields */ }

A pointer type used to identify entries in the linked hash map.

This is an opaque handle that can be used to directly access entries without key lookup. It provides O(1) access to entries.

By default, Ptr is non-generational, meaning that once an entry is removed, the pointer may be re-used for a new entry. With the generational feature enabled, Ptr includes generation tracking that will panic or return None when attempting to use a stale pointer after its entry has been removed.

Examples

use tether_map::Entry;
use tether_map::LinkedHashMap;
use tether_map::Ptr;

let mut map = LinkedHashMap::new();
let ptr = match map.entry("key") {
    Entry::Vacant(entry) => entry.insert_tail(42).0,
    Entry::Occupied(entry) => entry.ptr(),
};

// Use the pointer for direct access
assert_eq!(map.ptr_get(ptr), Some(&42));

// Remove the entry
map.remove(&"key");

// Using the stale pointer is a logic error but will not panic
assert_eq!(map.ptr_get(ptr), None);

// Insert a new entry, which may reuse the same Ptr value
map.insert("key", 100);

// The old pointer is stale, but may point to the new entry by coincidence
// This may work or not depending on whether the same Ptr value was reused:
// assert_eq!(map.ptr_get(ptr), Some(100));

With the generational feature enabled, using a stale pointer will return None or panic:

use tether_map::Entry;
use tether_map::LinkedHashMap;
use tether_map::Ptr;

let mut map = LinkedHashMap::new();
let ptr = match map.entry("key") {
    Entry::Vacant(entry) => entry.insert_tail(42).0,
    Entry::Occupied(entry) => entry.ptr(),
};

// Remove the entry
map.remove(&"key");

// Using the stale pointer will return None or panic
assert_eq!(map.ptr_get(ptr), None);

// Insert a new entry, which may reuse the same Ptr value
map.insert("key", 100);
// The old pointer is stale, so this will definitely return None
assert_eq!(map.ptr_get(ptr), None);

Trait Implementations

impl Clone for Ptr

fn clone(&self) -> Ptr

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Ptr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for Ptr

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<K, T, S> Index<Ptr> for LinkedHashMap<K, T, S>

type Output = T

The returned type after indexing.

fn index(&self, index: Ptr) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<K, T, S> IndexMut<Ptr> for LinkedHashMap<K, T, S>

fn index_mut(&mut self, index: Ptr) -> &mut Self::Output

Performs the mutable indexing (container[index]) operation.

impl Ord for Ptr

fn cmp(&self, other: &Ptr) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Ptr

fn eq(&self, other: &Ptr) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Ptr

fn partial_cmp(&self, other: &Ptr) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Ptr

impl Eq for Ptr

impl StructuralPartialEq for Ptr